The present invention relates to fluid pressure driven motors and, in particular, it concerns a bidirectional fluid pressure driven piston motor with a pressure compensation chamber.
U.S. Pat. No. 7,258,057 teaches various implementations of a water-driven piston motor. Referring particularly to FIGS. 14 and 15 thereof, which are reproduced here as FIGS. 1A and 1B, respectively, and referring to original reference numerals in parentheses, there is shown an assembly in which a cylinder (13) is mounted rotatably on a valve body (45). The cylinder has a central opening which selectively overlaps with one or other of two apertures (38), (39) as a function of the angle of the cylinder. When fluid pressure is delivered to channel (113) and channel (114) is open to drain, the cylinder opening overlaps aperture (38) while deflected to angles right-of-center, resulting in a driving pressure acting to extend piston (100) on the right half of a crankshaft motion. When the cylinder reaches center-bottom, the cylinder opening no longer overlaps aperture (38) and, as the cylinder continues to left-of-center, the opening starts to overlap aperture (39), thereby allowing draining of the cylinder contents to channel (114) during the left half of the crankshaft motion. By providing three or more cylinders out of phase, it is possible to ensure that at least one is effective to provide a driving torque to the crankshaft at any moment. By providing fluid pressure to channel (114) and opening channel (113) to drain, motion can be driven in a reverse direction of rotation.
As shown in FIG. 1B (original FIG. 15), in order to minimize leakage from the pressurized input channel into the cylinder during the part of the cycle in which the pressure-supplying aperture is sealed, each aperture is provided with a seal configuration which includes an elastomeric sleeve (107), (111) which biases a thin cap or hard sealing material (108), (112) to conform against the cylindrical inner surface of the cylinder head.